The present invention pertains to the art of welding, and more particularly to welding wires used in welding machines.
U.S. Provisional Application Ser. No. 60/298,555 filed Jun. 15, 2001 entitled xe2x80x9cxe2x80x98Sxe2x80x99 Shaped Cast In Wirexe2x80x9d is incorporated herein by reference.
One of the lingering problems in the field of welding is the consistent formation and placement of a quality weld bead. Various measures have been employed to achieve this goal. For instance, the waveform of the welding current has been closely controlled to achieve better weld bead formation and weld bead quality. In addition, the feed rate of a weld wire has been controlled to produce a higher quality weld bead. The composition of the consumable weld wire and various types of shielding gases used during the welding process have been employed to achieve higher quality weld beads. Although many of these techniques have significantly improved weld bead quality, consistent weld bead placement on a workpiece has remained illusive.
One of the remaining problems with obtaining a consistent weld bead placement on a workpiece is the position of the weld wire relative to the workpiece as the weld bead is being formed. It has been found that when the position of the tip of the weld wire varies relative to the welding tip of a welder, the consistency of the weld bead placement degrades. It is common industry practice to feed a xe2x80x9ckilledxe2x80x9d weld wire to a welder during the welding process. A xe2x80x9ckilledxe2x80x9d weld wire is a weld wire that has had its shape memory removed prior to the weld wire being wound onto a reel, spool, container, or the like. When the weld wire is wound on the reel, spool, container, or the like, the weld wire adopts a new shape as it is being wound. When the weld wire is unwound from the reel, spool, container, or the like, the weld wire adopts a new shape during the unwinding process. As a result, the shape of the unwound wire will vary along the longitudinal length of the unwound weld wire. Once the unwound weld wire is cut into various sections, the unwound wire retains its adopted shape obtained when being unwound from the reel, spool, container, or the like. Further modifications to the shape of the weld wire can result during the cutting process and/or while the weld wire is positioned for being cut and/or as the weld wire is fed into the welding machine. Since the weld wire has no memory, the weld wire constantly modifies its shape as it passes through the weld gun, thus resulting in inconsistent positioning of the weld wire as it exits the welding tip of the welding gun or torch. This inconsistent positioning of the weld wire results in inconsistent placement of the weld bead onto a workplace.
Various techniques have been used by operators to minimize this attribute of the weld wire. One technique is for the operator to cut the weld wire in certain positions relative to the unwound weld wire to obtain a desired weld wire profile for the cut weld wire section. The operator can further modify the shape of the weld wire by hand as he/she deems fit. Although these techniques can improve weld bead placement on a workpiece, the weld bead placement consistency varies widely between operator and from the use of different cut sections of the weld wire.
When the weld wire is automatically fed into a welding machine, such as in a robotic welder, problems with consistent weld bead placement can be severe. Typically, robotic welders follow a predefined path when forming a weld bead. The varying position of the weld wire as it exits the welding tip of the robotic welder can cause significant weld bead placement deviation during the welding process. During manual welding, the operator has the ability to attempt to correct and/or compensate for weld bead placement; however, such techniques are inapplicable to robotic welders.
In addition to the problems associated with the use of xe2x80x9ckilledxe2x80x9d wire in obtaining consistent weld bead placement, the xe2x80x9ckilledxe2x80x9d wire is more susceptible to bending and the formation of kinks in the weld wire as the weld wire travels through the weld gun, thereby resulting in undesired weld bead placement and the possibility of a low quality weld bead.
In view of the persistent problems of weld bead placement during a welding operation, there is a demand for an improved weld wire which addresses the problem associated with consistent weld bead placement onto a workpiece.
The present invention pertains to an improved weld wire and a process for making the improved weld wire for use in various types of welding machines. These welding machines can include automated welders and manual welders. In addition, the weld wire can be used in various types of welding processes such as MIG, MAG, or STT welding, or in other types of welding processes wherein a consumable electrode is utilized to form a weld bead onto a workpiece. The improved weld wire in accordance with the present invention involves the utilization of a weld wire that has a shape memory imparted onto the weld wire prior to and/or at the time the weld wire is wound onto a reel, spool, container, or the like, and which shape memory is fully or partially retained by the weld wire as the weld wire is unwound from the reel, spool, container, or the like. The use of weld wire with a shape memory is a deviation from common industry practice that teaches that weld wire that is fed into a welding machine should have little or no shape memory. The common practice in the industry was to xe2x80x9ckillxe2x80x9d the wire or otherwise remove the shape memory of the wire prior to winding the weld wire onto a reel, spool, container, or the like. It was commonly believed that a weld wire having a shape memory would adversely affect the unwinding of the weld wire from the reel, spool, container, or the like during the welding process and would further be more susceptible to kinks, bends and other problems as the weld wire is fed through the welder during the welding process. Furthermore, it was commonly believed that a weld wire with shape memory would aggravate the problem associated with consistent weld bead placement. Surprisingly, the use of a shape memory weld wire in accordance with the present invention results in the formation of a weld bead having better consistent placement during the welding operation and the formation of higher quality weld beads than weld beads formed by xe2x80x9ckilledxe2x80x9d weld wires. The use of a weld wire with shape memory has also been found to form a more robust weld bead during the welding process. Furthermore, the use of a weld wire with shape memory has been found to reduce the occurrence of bends and kinks in the welding wire as it is being cut for use during the welding process and/or during the feeding of the weld wire through a welding machine during the welding process. It has also been found that the use of a weld wire with shape memory reduces or substantially eliminates the operator""s control over the weld wire shape. In the past, weld wire that has been xe2x80x9ckilledxe2x80x9d could be cut at various locations to help improve the weld bead placement. However, the shape of the cut weld wire was inconsistent from one operator to the next, and furthermore the shape of the weld wire was inconsistent from one cut section to another. As a result, the operator had significant control over the resulting consistency of weld bead placement. The use of a weld wire with shape memory in accordance with the present invention overcomes this inconsistency problem since similar cut weld wire sections will have substantially the same shape from one cut section to the next. In addition, the weld wire with shape memory will resist further shape modifications during the cutting process and as the weld wire is fed through a welder. Consequently, as the weld wire with shape memory is fed through the contact tip of a welding gun, the weld wire will be similarly positioned relative to the tip from one cut section to the next, thus forming a more consistent weld bead placement during the welding operation.
In accordance with the present invention, there is provided a weld wire with a predefined shape memory imparted onto the welding wire prior to the welding wire being wound onto a reel, spool, container, or the like. The shape memory of the weld wire is fully or partially retained by the weld wire as the weld wire is wound and unwound from a reel, spool, container, or the like and as the weld wire is fed through a welding machine. The shape memory on the weld wire can be formed from a variety of processes such as, but not limited to, a casting process. The shape memory imparted onto the weld wire can occur during the formation of the weld wire and/or by a process subsequent to the formation of the weld wire. In one embodiment, the weld wire is formed by an extrusion process wherein the weld wire is imparted a shape memory during the extrusion process. As can be appreciated, the weld wire can be formed by other processes. In one aspect of this embodiment, the desired shape memory of the weld wire is at least partially imparted onto the weld wire as the weld wire is formed by the extrusion process. In another aspect of this embodiment, the desired shape memory imparted onto the weld wire is formed subsequently to the formation of the weld wire by an extrusion process or by some other process. In this aspect, the shape memory imparted onto the weld wire during the formation of the weld wire can be partially or fully removed from the weld wire and subsequently the desired shape memory is then imparted on the weld wire by one or more processes, such as, but not limited to, a casting process.
In another aspect of the present invention, the desired shape memory imparted onto the weld wire is selected to maximize the consistency of weld bead placement on a workpiece. In one embodiment, the shape memory of the weld wire is imparted substantially in one plane along the longitudinal length of the weld wire. In one aspect of this embodiment, the cut weld wire, when laid upon a flat ground surface, rises above the flat ground surface less than about 6 inches, generally less than about 5 inches, typically less than about 4 inches, more typically less than about 3 inches, even more typically less than about 2 inches, and still even more typically less than about 1.5 inches. As can be appreciated, the less the weld wire deviates from the single plane, the better the consistency of weld bead placement typically obtained. In another embodiment, the shape memory imparted on the weld wire is in multiple planes. In this embodiment, the predefined shape of the shape memory on the weld wire has a repeating pattern which exists in multiple planes and which results in a more consistent weld bead placement during the welding process. In one aspect of this embodiment, the deviation from the predefined shape memory in multiple planes is less than about 6 inches, generally less than about 5 inches, typically less than about 3 inches, more typically less than about 2 inches, and even more typically less than 1.5 inches. As can be appreciated, better weld bead placement is typically obtained as the deviation from the desired shape memory that has been imparted onto the weld bead approaches zero.
In still another embodiment, the desired shape memory imparted onto the weld wire is a waveform; however, as can be appreciated, other shapes for the shape memory can be imparted onto the weld wire. In one aspect of this embodiment, the maximum amplitude of the waveform is substantially the same throughout the length of the cut section of the weld wire. The maximum amplitude of each half cycle of the cut weld wire can vary sightly depending upon the position of the weld wire on the reel, spool, container, or the like as it is being unwound from the reel, spool, container, or the like. Furthermore, the maximum amplitude of the half cycle of the cut weld wire can also vary depending on the weld wire diameter. Generally, the deviation of the maximum amplitude of each half cycle within one cycle of the cut weld wire varies less than about 6 inches, typically less than about 4 inches, more typically less than about 2 inches, and even more typically less than about 1 inch. As can be appreciated, the less deviation from maximum amplitude to maximum amplitude for each half cycle of the cut weld wire results in better consistency of weld bead placement typically obtained. In another aspect of this embodiment, the maximum amplitude of each half cycle of the cut weld wire is generally less than about 60 inches, typically 5-40 inches, more typically about 10-22 inches, and even more typically about 14-20 inches. As can be appreciated, other maximum amplitudes can be used for various types of welding operations. In still another aspect of this embodiment, the length of each cycle of the cut weld wire section is the same or substantially the same for adjacent positioned cycles. The length of each cycle of cut weld wire section can vary depending on the position of the weld wire as it is being unwound from a reel, spool, container, or the like. The diameter of the wire can also affect the length of each cycle of the cut weld wire section. Generally, the deviation of the length of each weld wire section is less than about 15 inches, typically less than about 10 inches, more typically less than about 6 inches, and even more typically less than about 5 inches, and still even more typically less than about 2 inches. As can be appreciated, the less deviation from the length of the cycle to the cycle of the cut weld wire, the better the consistency of the weld bead""s position will be typically obtained. The length of each cycle of the cut weld wire sections will vary depending on the particular weld operation. Generally, the length of each cycle of the cut weld wire section is less than about 200 inches, and typically less than about 150 inches, and more typically about 40-120 inches, and even more typically about 50-100 inches, and still even more typically about 60-90 inches. As can be appreciated, other wire dimensions can be used. In still yet another embodiment of the present invention, the imparted shape memory on the weld wire creates a waveform for a cut section of the weld wire, wherein each half cycle has a substantially semi-circular shape, wherein each half cycle for each cycle of the cut weld wire section has substantially the same radius.
In still yet another aspect of the present invention, the shape memory imparted onto the weld wire is selected to improve the quality of the weld bead and facilitate in the formation of the weld bead. In one embodiment, the shape memory imparted onto the weld wire causes the weld wire to flip as the weld wire is fed through the welding tip of the welding gun. This flipping phenomenon results in the welding wire always being in the same or substantially in the same position relative to the welding tip as the welding wire is fed through the welding tip, thereby resulting in a more consistent position of the weld bead. The number of flips of the weld wire is typically dependent on the maximum amplitude of each cycle of the weld wire, the length of the cut section of the weld wire, the diameter of the weld wire, and the length of the cycles of the weld wire. In another embodiment, the shape memory imparted onto the weld wire inhibits or reduces the susceptibility of the weld wire being bent or otherwise kink as it is being unwound from a reel, spool, container, or the like and/or as the weld wire is fed through the weld gun or torch or other components of the welding machine. When the weld wire bends, kinks or otherwise does not properly feed through the welding machine during the welding process, the consistency of position of the weld bead and/or the quality of the weld bead can deteriorate. The use of the shape memory weld wire reduces such incidences since the imparted shape memory resists changes in such imparted shape, thereby improving the consistency of high quality weld beads and better ensuring consistent placement of the weld bead during the welding process. In still another embodiment, the shape memory imparted w onto the weld wire facilitates in the heating of the weld wire at the welding tip of the welding gun. The imparted shape memory onto the welding wire causes the welding wire, as it travels through the welding tip of the welder, to engage the side of the welding tip prior to exiting the welding tip. This friction creates heat, which in turn facilitates in the melting of the tip of the weld wire during the welding process, thereby achieving a higher quality and more robust weld bead during the welding process.
It is the primary object of the present invention to provide an improved weld wire which obtains better placement consistency of the weld bead onto a workpiece.
It is another and/or alternative object of the present invention to provide a weld wire which has an imparted shape memory which lies in a substantially single plane.
It is still another and/or alternative object of the present invention to provide a weld wire which has reduced susceptibility to bending and/or kinks as the weld wire is unwound from a reel, spool, container, or the like and/or as the weld wire is fed through a welding machine.
It is yet another and/or alternative object of the present invention to provide a weld wire which facilitates in the heating of the weld wire during the welding process.
It is still yet another and/or alternative object of the present invention to provide a weld wire which forms a more robust weld.
It is a further and/or alternative object of the present invention to provide a weld wire which reduces inconsistency of shape when being cut into sections by an operator.
It is yet a further and/or alternative object of the present invention to provide a weld wire which can be successfully used in robotic welding to obtain consistent placement of the weld bead onto a predefined path on a workpiece.
It is still yet a further and/or alternative object of the present invention to provide a weld wire having a shape memory in the form of a waveform.
It is another and/or alternative object of the present invention to provide a weld wire which has a desired shape memory imparted on the weld wire after the weld wire has been formed and prior to the time the weld wire is wound onto a reel, spool, container, or the like.
These and other objects of the invention will become apparent to those skilled in the art upon reading and understanding the following detailed description of the preferred embodiments taken together with the drawings.